Krill oil increases plasma omega-3 fatty acids more than fish oil in healthy adults: a double-blind randomized controlled trial

BACKGROUND: Omega-3 fatty acids (ω-3 FAs), particularly EPA and DHA, are recognized for their health benefits. However, their circulating levels after supplementation may be modulated by several factors, including sex, carriage of the apolipoprotein E ε4 (APOE4) allele, and the chemical form of the supplement. Krill oil delivers ω-3 FAs primarily as phospholipids, whereas fish oil provides them as triglycerides. OBJECTIVES: This study aimed to compare EPA and DHA concentrations after supplementation with krill oil and fish oil and assess whether sex and APOE4 genotype modify responses to supplementation. METHODS: This double-blind, randomized clinical trial included 72 healthy adults (53 females, 19 males) matched for age and BMI. Participants received 1.1 g/d ω-3 FAs through either krill oil (n = 36) or fish oil (n = 36) for 12 wk. Plasma FAs were measured at baseline and at weeks 1, 2, 4, and 12 by GC-flame ionization detection. Differences in plasma ω-3 FAs concentrations by treatment, sex, and APOE4 status were analyzed. RESULTS: Time-by-treatment interactions were significant for plasma delta over baseline concentrations of EPA (P = 0.0001) and DHA (P = 0.005), with krill oil resulting in ∼1.5-fold higher Δ EPA and Δ DHA compared with fish oil. The time-by-sex interaction was significant only for EPA (P = 0.026), with females having a 1.5-fold greater increase than males at 12 wk. After supplementation with either krill oil or fish oil, APOE4 carriers had 3-fold and 1.6-fold higher EPA and DHA, respectively, compared with baseline; however, these increases were not significantly different from those found in noncarriers. CONCLUSIONS: Krill oil increased plasma ω-3 FAs more than fish oil, regardless of APOE4 genotype. Individuals with higher ω-3 FA requirements may achieve adequate enrichment with lower doses of krill oil compared with fish oil supplementation. This trial was registered at clinicaltrials.gov as NCT04279743.